Gas discharge device



May 20, 1958 HSIUNG HSU GAS DISCHARGE DEVICE Filed June 20, 1955 FIGS. 2AND 4 INPUTCURRENT INVENTORZ HSIUNG HSU.

} BY HI ATT RNEY.

GAS DISCHARGE DEVICE Hsiung Hsu, Liverpool, N. Y., assignor to GeneralElectric Company, a corporation of New York Application June 20, 1955,Serial No. 516,532

13 Claims. (Cl. 313-71) My invention relates to improvements in gasdischarge devices and pertains more particularly to improvements in gasamplifier tubes.

One type of gas amplifier tube generally comprises a sealed envelopecontaining a gaseous filling or ionizable medium, such as xenon, a maincathode, a main anode, and an auxiliary cathode. In the tube there areseparate discharge paths for a load current and an ionizing current. Theenergizing potential required to draw the load current between the maincathode and the main anode is set at a value substantially below thevalue required to produce ionization of the filling or ionizable medium.A higher potential is applied between the auxiliary cathode and the mainanode to maintain a separate ionizing or auxiliary discharge. Theauxiliary discharge ionizes the gaseous filling for thereby convertingit into a plasma constituted of positive ions and detached, freenegative electrons. The free, negative electrons are attracted to themain anode and the heavier positive ions tend to surround the maincathode and fill the load current discharge path or inter-electroderegion between the main cathode and anode. Thus, the positive ions serveto neutralize the electron space charge surrounding the main cathode andserve eifectively as a low impedance conductor extending between themain cathode and the main anode. Due to these elfects the tube outputcurrent is generally substantially larger than the input current or, inother words, the tube provides a current amplification effect. Theamount of current output depends on the density of the plasma betweenthe main cathode and anode and the amount of ionizing or input currentrequired to provide the plasma.

Now, in the ordinary gas amplifier tube the input current compriseselectrons which travel toward and into the inter-electrode regionintermediate the main cathode and anode. These electrons generate theplasma in the inter-electrode region which is required for the operationof the tube. Additionally, the input current comprises a substantialnumber of electrons which do not enter the inter-electrode region butwhich flow directly from the auxiliary cathode to the main cathode andto the edges and surface portions of the anode including the sides ofthe anode opposite the main cathode. These last-mentioned electrons areundesirable in that they increase the input current required to operatethe tube without assisting in the generation of useful plasma in theinter-electrode region between the main cathode and anode. Thus, thecurrent amplification eifect of the tube is decreased. This limitssubstantially the applications of the tube. Additionally, the mentionedundesirable electrons increase substantially the tube noise.

Accordingly, the primary object of my invention is to provide a new andimproved current amplification device.

Another object of my invention is to provide a current amplifying gastube including new and improved means for increasing the currentamplification effect thereof.

Another object of my invention is to provide a current amplifying tubeincluding new and improved means for reducing the current input requiredto provide a predetermined amplified current output.

Another object of my invention is to provide a current amplifying gastube including new and improved means for reducing noise in theoperation thereof.

Still another object of my invention is to provide a new and improvedcurrent amplifying device including means adapting the device forincreased applications.

Further objects and advantages of my invention will become apparent asthe following description proceeds and the features of novelty whichcharacterize my invention will be pointed out in particularity in theclaims annexed to and forming part of this specification.

In carrying out the objects of my invention I provide a sealed envelopecontaining an ionizable medium, a main cathode and a main anode incooperative spaced relation and an auxiliary cathode adapted formaintaining an ionizing discharge and thereby generating a plasmabetween the main cathode and anode. Cooperating with the auxiliarycathode is means adapted for directing the ionizing discharge into thespace between the main anode and main cathode and for minimizing thedirect effects of the discharge on the main cathode and anode.Additionally, the last-mentioned means may be adapted for collectingelectrons emitted from the main cathode.

For a better understanding of my invention. reference may be had to theaccompanying drawing in which:

Fig. l is an enlarged elevation view of a gas discharge device partiallybroken away to illustrate an embodiment of my invention incorporatedtherein;

Fig. 2 is an enlarged sectional view taken along the lines 2-2 in Fig. land looking in the direction of the arrows.

Fig. 3 is a schematic circuit diagram of an amplifier system using thetube shown in Figs. 1 and 2;

Fig. 4 is a cross-sectional view similar to that of Fig. 2 andillustrating another embodiment of my invention;

Fig. 5 is a cross-sectional view similar to that of Fig. 2 andillustrating still another embodiment of my invention;

Fig. 6 is a schematic circuit diagram of an. amplifier system using thetube shown in Fig. 5; and

Fig. 7 is a graph that shows the output current versus input current ofdiiferent types of gas amplifier tubes including tubes incorporating myinvention.

Referring to Fig. 1, there is shown a gas amplifier tube incorporatingan embodiment of my invention and generally designated 1. The tube 1comprises a sealed insulative envelope 2 and an insulative base 3carrying a plurality of pins or prongs 4 electrically connected to leads(not shown) extending in a sealed manner through the lower end of theenvelope and adapted for providing electrical connections to variouselectrode elements contained in the envelope. Additionally, the envelope2 is charged or filled with an ionizable medium or filling which may bexenon gas or any of the other gases which are well-known by thoseskilled in the art to be suitable for use in gas tubes of the presentlyconsidered type.

In the envelope 2 the electrodes are supported in spaced insulatedrelation between a pair of spaced insulators 5 which may comprise theconventional mica disks. As perhaps better seen in Fig. 2 the mentionedelectrode elements include a main cathode 6 which may be of the familiarindirectly heated type comprising a substantially fiat elongatedmetallic sleeve 7 coated with a suitable electron emissive material andcontaining a suitable filamentary heater 8.

Supported between the disks 5 in spaced relation to the main cathode 6is a main anode 10. The anode 1i) may comprise a three sided sheet metalstructure as shown or may be of any similar construction which wouldcause it to fit almost completely about the cathode J1 and thereby adaptit for maximum collection of electrons emitted by the cathode 6 whileproviding a suitable entrance for an ionizing discharge into theinter-electrode region between the main cathode and anode.

Positioned between the insulative supports in spaced relation to themaincathode and anode and disposed in front of the entrance into the mainanode is a second or auxiliary cathode 11. The auxiliary cathode It mayalso be of the indirectly heated type and, as shown, it

may comprise a cylindrical metal sleeve 12 having a in construction tothe anode and is disposed so that the side edges thereof extend topositions adjacent the edges of the main anode 10 and the open side ordischarge aperture provided by the shield is adjacent to or coincideswith the entrance to the inter-electrode region between the main cathodeand anode. Provided in the shield 14 and suitably secured to theopposite side walls is a pair of elongated members 15 adapted forproviding a discharge aperture. Additionally, fitted over the ends ofthe auxiliary cathode I1 and covering the ends of the shield 14 aresuitable metal caps or end shields I16 The tube described to this pointmay be operated in a circuit such as that shown in Fig. 3. In thisfigure are shown a low-potential load-current-energizing source 17 and arelatively higher potential auxiliarly-discharge-energizing source 18.Any suitable source (not shown) may be providedfor energizing thecathode heaters 8 and 13.

One side of the source is connected through a utilization' device, whichmay be a loudspeaker 20, to the main anode and the other side isconnected to the main cathode and, thus, the source 17 is adapted formaintaining the smaller non-ionizing potential between the main cathode6 and the anode 10. This is preferably a low impedance source. This typeof source is provided because of the fact that although it need notprovide much voltage it must, as'will appear, be capable of deliveringto the output current utilization device or loudspeaker 29 a substantialsignal-bearing current such as a current which may have an average valueof the order of one to several amperes.

The source 18, in turn, is required to be capable of providing arelatively higher potential but need not be capable of providing aparticularly large continuous average current. This is due to the factthat the source is serves to energize the relatively efficientlow-current iOIllZ- ing-discharge.

In the arrangement described the main anode and the main cathode serveconjointly as an anode for attracting and receiving electrons from theauxiliary cathode 11, thereby to establish the auxiliary or ionizingdischarge. Thus, the source 18 is connected between the auxiliarycathode 11 and the side of the source 17 connected to the main cathodethrough a signal generating means 21 which may be one of any number ofsuitable well-known devices.

Briefly considered, during operation of the just-do scribed circuit, theauxiliary cathode 11 provides an ionizing discharge which is effectivefor ionizing the gas or ionizable medium thereby to provide a plasmaindicated by the stippling generally designated 24 in Fig. 3. Thus,positive ions are provided for neutralizing the space charge between themain cathode and anode thereby to increase greatly the emission from themain cathode or amplifying the current in the output circuit or circuitcoupled to the utilization device adapted for being operated by theoutput current.

Now, I have found that in a system such as that justdescribed, asubstantial number of electrons comprising the ionizingdischarge tend toflow to the main cathode and the surfaces of the main anode before theyare able to produce effective plasma between the main cathode and anode.These electrons are wasted in that they do not assist in neutralizingthe space charge and tend to increase the current input required for agiven desired output current, for example, and as indicated by the curvedesignated A in Fig. 7, an input current of one milliarnpere will resultin an output current of only twenty milliamperes. This is not asubstantial amplification. A" 'itionally, the electrons which flow tothe main cathode and anode without contributing substantially to theproduction of plasma in the region between the main cathode and anodehave the effect of causing substantial tube noise. Accordingly, myinvention is intended to 'rinirnize the amount of wasted electrons inthe ionizing discharge, thereby to reduce the input current required toobtain a predetermined amplified output current and to reduce noise.

As seen in Figs. 1-3 an embodiment of my invention may include a singleelongated electrode element 25 mounted between micas 5 and disposed in adirect or straight line path between the auxiliary and main cathodes andadjacent the latter. Thus, with respect to the auxiliary cathode, themain cathode is located in the shadow of the element 25, or consideredfrom another viewpoint the element 25 is adapted for splitting ordividing the ionizing discharge or stream of electrons in substantiallythe manner illustrated by the arrows in Fig. 3. As shown, the element 25is allowed to float electrically or if desired it maybe biased slightlynegatively with respect to the auxiliary cathode 11. Accordingly, thestream of electrons comprising the ionizing discharge is split anddiverted from the edge of the main cathode and directed into theinter-electrode regions or spaces on either side of the main cathode 6and between the main cathode and anode for producing plasma betweenthese electrodes. Thus, eiectrons are not Wasted on the edge of the maincathode and greater concentration of positive ions or plasma is providedwhere it is most useful to neutralize the space charge with the resultthat emission from the main cathode and output current arecorrespondinglyv increased. The advantage of this form of my inventionis perhaps better appreciated by reference to the curves shown in Fig.'7 whereby it is shown that a given desired output current ofapproximately two-hundred milliamperes may be obtained with an inputcurrent of only one milliampere.

Additionally, tie diversion of the auxiliary discharge from the edge ofthe main cathode reduces substantially noise tube operation. Reductionof wasted electrons and noise are further eifected by the shield 24 andthe members 15 which prevent electrons from flowing dircct ly to theedges and outer surfaces of the main anode.

It is to be understood that while I have illustrated the ciement 25 asbeing Y-shaped in cross-scction it may assume any desiredcross-sectional configuration throughout its length. For example, I havefound that a flat metal strip or a metal rod are suitable for splittingthe electron stream and diverting the electrons in the abovedescribedmanner. Additionally, by carrying the potential applied to the element25 it is possible to determine and variably control the shadowing effectof the element of the main cathode.

In Fig. 4 is illustrated a modified form of my invention incorporated ina tube generally designated in. In this embodiment the envelope,electrode supports, main cathode, main anode and auxiliary cathode maybe identical in structure and purpose to those described above withregard to Figs. l3 and are accordingly re erred to by similar referencecharacters. The Fig. 4 embodiment differs, however, in that it includesan auxiliary cathode shield 26 which is relatively narrower than themain anode and includes side portions which extend up to the anodeentrance and define a discharge aperture that is smaller than the anodeentrance. Additionally, this form of my invention includes an elongatedconductive element mounted between the usual top and bottom micas andwhich extends radially for a substantial distance in the straight linepath between the cathodes. Element 27 can be allowed to floatelectrically or be biassed slightly negative with respect to theauxiliary cathode to cause the electron stream to become split ordivided with portions thereof diverted from the edge of the main cathode6 and directed into the spaces or inter-electrode regions intermediatethe main cathode and anode. Additionally, the shield 126 causes theouter portions of the divided stream to be diverted from the anode 10and into the portions of the inter-electrode regions immediatelyadjacent the main cathode. This results in concentration of theresulting plasma in the portions of the space charge adjacent thecathode where it is efiective in accordance with the invention, tocontrol the space charge and the output current of the device.Additionally, the just-described shielding structure prevents electronsfrom impinging upon the edges and outer sides of the main anode; Thus,the structure illustrated in Fig. 4 is effective for minimizing theinput current required to obtain a predetermined amplified outputcurrent in a manner generally similtnar to that of the device of Fig. 2and also illustrated in Pig. 7. Additionally, noise is reduced in amanner similar to that described above.

in Fig. 5 is illustrated another embodiment of my invention in which theenvelope, electrode supports, main cathode, main anode, auxiliarycathode and shield may be identical in structure, and purpose, andnumerical designation to those illustrated in Figs. 1-3. The structureof Pig. 5 is different, however, in that it includes an auxiliarydischarge splitting electrode element 30 which may be supported betweenthe top and bottom micas and disposed in a straight line path betweenthe cathodes, as shown, element Ed is located adjacent the exit apertureof the auxiliary cathode It and on the auxiliary cathode side ofelectrode 32 located in the same path between the element 34) and themain cathode 6. Thus, the electrode 31 is in the shadow of the elementSt and adjacent the main cathode 6. As before, stream-splittingelectrode 30 can be allowed to float electrically or biassed slightlynegative relative the auxiliary cathode. The electrode 31, as seen inPig. 6, is adapted for being connected to the anode 1d and to thepositive terminal of source 17 through the utilization device, hereshown as a loudspeaker 2%.

During the operation of the system shown in Fig. 6, the ionizingdischarge or electron stream emanating from the auxiliary cathode 11 issplit by the element 30 and thereby diverted from the electrode 31 andcathode 6 and divided into two leg portions. Thereafter, the electronscomprising the leg portions of the split stream tend to impinge upon theside wall portions of the main anode til. However, since the main anodeto which the electrode 31 is connected is positive relative to the maincathode, the element 31 is effective for attracting the legs of theelectron stream inwardly. This results in the electrons entering thespace charge or inter-electrode region adjacent the main cathode,resulting in greater concentration of effective plasma in the portionsof the inter-electrode regions immediately adjacent the cathode. Itfurther results in avoidance of substantial electron impingement uponthe walls of the main anode. As explained above in connection with theother embodiments, reduction of the input current required for apredetermined amplified output current and a substantial reduction ofnoise in the operation of the system are accomplished. Additionally, theinward attraction of the legs of the electron stream, as efiected by theelement 31,

results in the introduction of plasma between the main v cathode and theelement 31 while at the same time the main cathode 6 and electrode 31are ettectively shielded from the discharge stream. Now, inasmuch as theelement 31 is at anode potential, this results in current flow spanbetween the main cathode and the element 341 which results in increasedoutput current. As shown in Fig. 7, with my structure of Fig. 5 a givenoutput current of approximately four hundred milliamperes may beobtained with an input current of only one milliampere as cornpared withtwo hundred milliarnperes and twenty milliamperes obtainable with theversion of Figs. 2 and 4 and prior-known types, respectively.

Thus, it will be seen that I have provided a new and improved gasamplifier tube adapted for operating with a minimal input current forobtaining a predetermined amplified output current and therebyincreasing the current amplification eflect of the tube. Additionally,my device provides for substantial reduction of noise. Additionally,dueto the reduced requirement for input cur rent my device is applicablefor use in systems including components of relatively small currentoutput such as transistors. Thus, my invention is adapted for increasedapplications in electron circuits.

While I have shown and described specific embodiments of my invention, Ido not desire my invention to be limited to the particular forms shownand described, and I intend by the appended claims to cover allmodifications within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

l. A gas discharge device comprising; a sealed envelope containing anionizable medium, a main cathode and an anode in cooperative spacedrelation within said envelope, means including an auxiliary cathode inlaterally spaced relation to said main cathode for producing an ionizingdischarge to provide a conductive plasma be tween said main cathode andanode, and means for diverting said ionizing discharge from said maincathode and directing said ionizing discharge into the region b tweensaid main cathode and anode.

2. A gas discharge device comprising; a sealed envelope containing anionizable medium, a main cathode and an anode in cooperative spacedrelation within said envelope, means including an auxiliary cathode forproducing an ionizing discharge to provide a conductive plasma betweensaid main cathode and anode, and means effective for diverting saidionizing discharge: from the portion of said main cathode adjacent saidauxiliary cathode and directing substantially all of said ionizingdischarge into a portion of the region between said main cathode andanode adjacent said main cathode and substantially spaced from saidanode.

3. A gas amplifier tube comprising; a sealed envelope containing anionizable medium, means for carrying a load current through the tubecomprising a main cathode and a main anode in cooperative spacedrelationship, said anode including portions disposed on either side ofsaid main cathode, means including an auxiliary cathode in laterallyspaced relation to said main cathode for producing an ionizing dischargeto provide a conductive plasma between said main cathode and anode, andan element interposed between said main and auxiliary cathodes efiectivefor dividing said ionizing discharge thereby to shield said main cathodefrom the direct effects of such discharge and to direct a dividedportion of said dis-- charge into the inter-electrode region of eitherside of said main cathode.

4. A gas amplifier tube comprising; a sealed envelope containing anionizable medium, means for carrying a load current through the tubecomprising a main cathode and a main anode in cooperative spacedrelationship, said anode including portions disposed on either side ofsaid main cathode, means including an auxiliary cathode for producing anionizing discharge to provide a conductive plasma between said maincathode and anode, an element interposed between said main and auxiliarycathodes etfective for dividing said ionizing discharge thereby toshield said main cathode from the direct effects of said discharge andto direct a divided portion of said discharge into the inter-electroderegion on either side of said main cathode, and means limiting the outermargins of said divided portions of said discharge for effectingconcentration thereof in portions of said inter-electrode regionadjacent said main cathode.

5. A gas amplifier tube comprising; a sealed envelope containing anionizable medium, means for carrying a load current through the tubecomprising a main cathode and a main anode, said anode including sideportions disposed on either side of and in cooperative spacedrelationship with said main cathode, means including an auxiliarycathode for producing an ionizing discharge to provide a conductiveplasma between said main cathode and anode, a shield disposed about saidauxiliary cathode and including side portions extending adjacent to saidside portions of said anode, and an element interposed in a direct linepath between said cathodes, said element being effective for splittingsaid ionizing discharge thereby to shield said main cathode from thedirect effects of said discharge and to direct plasma producing portionsof said discharge into the inter-electrode regions on either side ofsaid main cathode, said shieldv being effective for reducing directeffects of said discharge on said main anode and to concentrate saidplasma producing portions of said discharge in portions of saidinter-electrode region immediately adjacent said main cathode.

6. A gas amplifier tube comprising; a sealed envelope containing anionizable medium, means for carrying a load current through the tubecomprising a main cathode and a main anode, said anode including sideportions disposed on either side of and in cooperative spacerelationship with said main cathode, the edge portions of said anodedefining an entrance for an ionizing discharge, means including anauxiliary cathode for producing an ionizing discharge to provide aconductive plasma between said main cathode and anode, a shield disposedabout said auxiliary cathode and including side portions extending tosaid anode entrance and defining an aperture smaller than said entrance,and an element interposed in a direct line path between said cathodeseffective for splitting said ionizing discharge thereby to shield saidmain cathode from the direct effects of said discharge and to directplasma producing portions of said discharge through said entrance andinto the inter-electrode regions on either side of said main cathode,said shield being effective for directing said plasma producing portionsaway from said anode and toward the lateral portions of said maincathode.

7. A gas amplifier tube comprising; a sealed'envelope containing anionizable medium, means for carrying a load through the tube comprisinga main cathode and a main anode, said anode including side portionsdisposed on either side of and in cooperative spaced relationship withsaid main cathode, the edge portions of said anode defining an entrancefor an ionizing discharge, means including an auxiliary cathode forproducing an ionizing discharge to provide a conductive plasma betweensaid main cathode and anode, a shield disposed about said auxiliarycathode and including elongated side portions extending to said anodeentrance and defining an aperture smaller than said entrance, and anelongated element interposed in and extending a substantial length of adirect line path between said cathodes, said element being effective forsplitting said ionizing discharge thereby to shield said main cathodefrom the direct effects of such discharge and to direct plasma producingportions of said discharge into the inter-electrode region on eitherside of said main cathode, said shield being effective for directingsaid plasma producing portions away from said side portions of said mainanode and toward the lateral portions of said main cathode.

8. Atgas amplifier tube comprising; a sealed envelope containing anionizable medium, means for carrying a load current through the tubecomprising a main cathode and a main anode in cooperative spacedrelationship,

means including an auxiliary cathode in laterally spaced relation tosaid main cathode for producing an ionizing discharge to provide aconductive plasma between said main cathode and anode, means effectivefor deflecting said ionizing discharge out of a straight line pathbetween said cathodes, and means effective for directing the deflectedportion of said discharge toward the inter-electrode region between saidmain cathode and anode.

9. A gas amplifier tube comprising; a sealed envelope containing anionizable medium, means for carrying a load current through the tubecomprising a main cathode and a main anode in cooperative spacedrelationship, means including an auxiliary cathode for producing anionizing discharge to provide a conductive plasma between said maincathode and anode, means effective for deflecting said ionizingdischarge out of a straight line path between said cathodes whereby saidmain cathode is substantially shaded from said ionizing discharge, andelectrode means adapted for directing the deflected portion of' saiddischarge toward the surface of said main cathode.

10. A gas amplifier tube comprising; a sealed envelope containing anionizable medium, means for carrying a load current through the tubecomprising a main cathode and a main anode, said anode includingportions on either side of and in cooperative spaced relationship withsaid main cathode, means including an auxiliary cathode for producing anionizing discharge to provide a conductive plasma between said maincathode and anode, an element interposed between said main and auxiliarycathodes effective for dividing said ionizing discharge thereby toshield said main cathode fro-m the direct effects of said discharge andto direct a divided portion of said discharge into the inter-electroderegion on either side of said main cathode, andan electrode interposedbetween said element and said main cathode adapted for being maintainedat a potential effective for attracting the divided portions of saiddischarge whereby said divided portions are caused to enter saidinter-electrode regions on either side of said main cathode adjacentsaid main cathode and substantially spaced from said main anode.

11. A gas amplifier tube comprising; a sealed envelope containing anionizable medium, means for carrying a load current through the tubecomprising a main cathode and a main anode, said anode includingportions on either side of and in cooperative spaced relationship withsaid main cathode, means including an auxiliary cathode for producing anionizing discharge to provide a conductive plasma betweensaid maincathode and anode, an element interposed in a direct line path betweensaid cathodes effective for dividing said ionizing discharge thereby toshield said main cathode from the direct effects of said discharge andto direct plasma producing portions of said discharge toward theinter-electrode regions on either side of said main cathode, and anelectrode interposed between said element and said main cathode adjacentsaid main cathode and electrically connected to said main anode, saidelectrode being adapted for effecting a convergence of the dividedportions of said discharge thereby to reduce direct effects of saiddischarge on said main anode and to direct said portions of saiddischarge into portions of the inter-electrode regions immediatelyadjacent said main cathode, said electrode being further effective forserving as an electron collector thereby to add to the load'current ofsaid tube.

12. A gas-filled current amplifying device comprising; a sealed envelopecontaining an ionizable medium, a main cathode and an anode incooperative spaced relation defining an inter-electrode region, meansfor producing an electron discharge to provide a conductive plasma insaid inter-electrode region, and discharge-controlling means effectivefor causing substantially all of the electrons comprising said dischargeto pass through said inter-electrode region before impinging upon anyportion of said main cathode and anode, thereby to provide maximumutilization of said discharge in producing plasma in said interelectroderegion.

13. A gas discharge device comprising; a sealed envelope containing anionizable medium, a main cathode and anode in cooperative spacedrelation Within said envelope, an auxiliary cathode in laterally spacedrelation to said main cathode and effective for producing an ionizingdischarge between said auxiliary cathode and main cathode and anode toprovide a conductive plasma between said main cathode and anode, and amember substantially completely shadowing the portion of said maincathode facing said auxiliary cathode and directing divergent portionsof said discharge into regions intermediate said main cathode and anodeand on opposite sides of said 10 main cathode, thereby to avoid directimpingement of said ionizing discharge on said main cathode and toprovide increased plasma density between said main cathode and anode.

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